Ghost Of GBU-28: When US Bunker-Buster Bomb Shattered Saddam's Last Hope

The American B-2 bombers flew for 13,000 km, carrying the GBU-57, a bunker-buster capable of striking underground facilities, and struck Iran's nuclear facilities to "obliterate" the country's atomic weapons programme. Now, US President Donald Trump says a regime change in Tehran will "Make Iran Great Again"; however, his ministers have said 'Operation Midnight Hammer' was not aimed at a regime change.

American air power has been deployed several times to "establish democracy" and fight terrorism in the Middle East. In 1990, when Iraqi dictator Saddam Hussein invaded Kuwait, the US launched Operation Desert Storm to fight the Iraqi forces. The air-land operation ended on February 28, 1991, but a day before the ceasefire, a bunker-buster bomb of the same class as GBU-57 was dropped from the air and is often credited with ending the first Gulf War. 

A GBU-28 being dropped by an F-15E. These bombs were initially developed for the F-111 but were later used by F-15 Strike Eagles as well.
Photo Credit: us.af.mil

GBU-28 - The Earth Penetrator

The 42-day aerial campaign launched by the US and the coalition forces obliterated Iraqi defences on the ground. Hell rained from the sky on Saddam's troops, forcing the dictator and his men to hide in concrete underground bunkers located several metres deep that could not be penetrated even by the BLU-109, a hardened bunker-buster used by the US since these bombs could not penetrate reinforced concrete beyond four to six feet.

The Iraqi commanders continued to direct the troops from these 40 concrete bunkers, often located at least 50 feet underground in Baghdad alone. The ground troops did not have much success in targeting them, and the US Air Force called for a magic bomb to be made to strike deep. And within four weeks, the innovative American engineers developed GBU-28.

From Concept to Combat

The engineers at Lockheed Martin, the US Air Force, and the Eglin Air Force base in Florida proposed a solid casing for the bomb to ensure it would not be crushed on impact with the bunker's thick concrete slabs. 

A dense penetrator version of BLU-109 - when dropped from a very high altitude from the B-52 Stratofortress, could penetrate the bunker - was proposed along with a hypersonic vehicle that could use its kinetic energy to pierce the slabs. Time was running against the engineers, and it could have taken several months to develop.

The Air Force proposed that the 8-inch barrels of the Army's M117 Howitzer could be the solution to the solid casing of the bomb because of weight and strength. The Watervalide Arsenal of the Army in New York was tasked to turn the howitzer barrels into bombs.

The work on the bomb started on February 1, and an official go-ahead was given on February 14.

The GBU-28 was developed from an 8-inch howitzer of the US Army. Within four weeks, it was ready for combat.
Photo Credit: https://man.fas.org/

It was decided by the Eglin base and Lockheed Martin engineers that the F-111 Aardvark would deliver the bomb, and its weight was reduced to approximately 4,000 kg to ensure it was ideal for the deep-strike fighter jet. Engineers at the air base worked a seven-day shift to deliver on time. The pellets of the bomb were being developed simultaneously, and the Lockheed engineers were working on the avionics suite of the F-111, and the nose of the BLU-109 had arrived to be used for the bomb.

A report said at least 15 design changes were made to the bomb's specifications. The nose cone for GBU-28 was secured and carefully welded, with wing attachments being made to the body of the bomb. Within three days, from the go-no-go decision on February 13, 1991, to February 16, the engineers worked day and night to deliver, and the first bombs were ready for assembly and loaded onto the C-130 cargo planes of the US Air Force.

The bomb casing arrived in Florida at the air base, and the process to fill the explosives began. Since the 13-foot casing of a bomb never came to the base, a hole was dug in the ground, and manually, engineers filled the casing with molten explosive in one bomb and concrete for a sled test in the other in a 37-hour-long process. The "dumb bombs" were fitted with a laser-guidance kit, and fins were attached to GBU-28's rear for aerodynamic stability. The bomb was ready for testing. On February 24, 1991, a GBU-28 was dropped from an F-111 in Nevada, and it penetrated the target at supersonic speed, burying itself at least 100 feet deep. 

F-111 Aardvark is a retired multi-role supersonic aircraft of the USAF used for reconnaissance and strategic bombing missions. It flew with the two GBU-28s
Photo Credit: us.af.mil

Later, the second bomb was used for the sled test and fired against a 22-foot thick steel reinforced concrete slab. The two tests were successful, and GBU-28 was ready for combat.

This was the first time a bomb moved from concept to combat in a short period, and with just two demonstrative tests before being used in action. It had a warhead weighing 4,400 pounds and an FMU-143 fuse - A type of high-velocity fuse mounted on bunker busters like the BLU-109 that can penetrate deep. It has a delayed-action tail-fuse which remains intact upon impact and gets activated after piercing the solid structure, causing delayed detonation and massive damage.

February 27, 1991

The two GBU-28 bombs were airlifted and taken to Taif in Saudi Arabia onboard the C-141 Starlifter of the US Air Force. They were fitted on the Aardvark, and the mission was to hit the Al Taji airbase, which survived the GBU-27 strikes so far from F-117 Nighthawks. Though Saddam was not present in the bunkers at Al Taji, its location just southwest of Baghdad made it significant.

Two F-111s with callsigns - 'Cardinal 7-1' and 'Cardinal 7-2', piloted by Lt Col Ken Combs and Maj Jerry Hust and  Col David White and Capt Tommy Himes respectively, took off. 

'Cardinal 7-1' and 'Cardinal 7-2' laser marked their targets. The first F-111 narrowly missed the target; it directed the second aircraft, piloted by Col White, to strike the primary target. They did not miss. The GBU-28 penetrated the bunker, and later, smoke from the vents of the structure confirmed an explosion deep within the ground. 

'Cardinal 7-1' was part of the strike package sent to attack Al-Taji airbase. It narrowly missed its target.
Photo Credit: https://www.dstorm.eu/

Only two GBU-28s were used throughout the war, and one successfully struck its target. A day later, Saddam's troops surrendered to the coalition forces, and the war was over. The bomb is often credited with instilling that fear among the Iraqi troops that their last haven is not safe anymore, though Iraqi troops had suffered extensive damage in the 40 days of the battle until GBU-28 was used.

The bombs were later deployed in Yugoslavia, the Second Gulf War in 2003, and Afghanistan. Israel was the first country to purchase these bombs from the US in 2005 after it intended it strike Iranian nuclear facilities with these munitions.

Trump And GBU-57

After yesterday's bombing, Trump claimed the GBU-57, a bomb of the same class as GBU-28, managed to inflict "monumental damage" to the Iranian nuclear facilities. "Obliteration is an accurate term!" he said, referring to the satellite images showing damaged sites in Iran.

Satellite images of Fordow, taken and distributed by Maxar Technologies, raise questions. The experts, news agency Reuters spoke to, looked at satellite imagery from Maxar Technologies and noted "unusual activity" at Fordow on Thursday and Friday, before the US attack. 

A long line of vehicles, waiting outside the facility entrance, is seen, indicating movement of the stockpile of near weapons-grade highly enriched uranium out of Fordow before the strike.

A senior Iranian source told Reuters that most of the near weapons-grade 60% highly enriched uranium had been moved to an undisclosed location before the US strike.

The "regime change" demand followed soon after the US declared Operation Midnight Hammer a success. In 1991, a bunker-buster bomb shattered Saddam's last hope. Thirty-four years later, the US hopes to do the same in Iran, but taking one step at a time - It starts with the destruction of underground nuclear facilities. 

Iran has not responded to US strikes, but its missile attacks on Israel continued.